Microbially accelerated corrosion of AA7075 aluminum alloy in simulated fuel–water conditions

Microbial contamination and the resulting corrosion in aircraft fuel system pose a serious threat to flight safety. Revealing the corrosion behavior and mechanism of fuel-degrading microorganisms on tank materials is crucial for developing effective mitigation strategies. In this study, the corrosion mechanisms of two representative hydrocarbon-degrading bacteria,Alcanivorax dieseloleiandMicrobacterium oxydans, toward AA7075 aluminum alloy, were systematically investigated. A combination of biofilm characterization, electrochemical testing, and surface/corrosion product characterization was employed. Both strains markedly accelerated the corrosion of AA7075, as evidence by the progressive decrease in polarization resistance and the pronounced rightward shift of the potentiodynamic polarization curves. Moreover, the difference between the pitting potential (Epit) and the corrosion potential (Ecorr) (ΔE=Epit−Ecorr) decreased due to microbial activities, indicating a pronounced tendency toward accelerated pitting corrosion. Corrosion morphology analysis revealed that both microbes promoted localized pitting corrosion. Furthermore, analysis of aviation kerosene composition indicated that both bacteria accelerated the degradation of C8 and C9 alkanes. These findings highlight the multiple threats of microbial contamination, material degradation, and fuel quality deterioration in fuel systems and underscore the need for targeted protection strategies for marine aviation operations.